JPH0667229A - Nonlinear optical material - Google Patents

Abstract

PURPOSE:To provide the nonlinear optical material having excellent blue light transmittance and the high nonlinear susceptibility in a molecular state by incorporating a compd. having an electron-donating part and electron-accepting part consisting of a group contg. a boron atom into the above-mentioned material. CONSTITUTION:This nonlinear optical material contains the compd. in which the electron-donating part and the electron-accepting part are bonded via at least one piece of multiple bonds. The electron-accepting part consists of a group contg. a boron atom. The boron atom is not bonded to the terminal vinyl group of a closed chain styryl group and the phosphor atom is not directly coupled to a vinyl group. The compd. is expressed by formulas I and II. In the formulas, R<1> and R<2> denote each an alkyl group, aryl group and hydrogen atom. Z<1> and Z<2> denote each a chalcogen atom and N-R<3>. R<3> is synonymous with R<1> and R<2>. W<1> to W<4> denote each a substituent; n<1> and n<3> denote each an integer from 0 to 4 and n<2> and N<4> each from 0 to 2.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to compounds useful as nonlinear optical materials.

[0002]

2. Description of the Related Art In recent years, a material having a non-linear optical material-a non-linearity between a polarization and an electric field, which appears when a strong optical electric field such as laser light is applied, has been attracting attention. Such materials are generally known as nonlinear optical materials and are described in detail in, for example, the following. "Nonlinear Optical Properties of Organic and Polymeric Materials"
C.S. Symposium Series 233 Edited by David Jay Williams (American Chemistry Society 1983)
Annual) "" Nonlinear Optical Properties of Organic
and Polymeric Material "ACS SYMPOSIUM SERIES 23
3 Edited by David J. Williams (American Chemical Society,
1983) ”,“ Organic Nonlinear Optical Materials ”Masao Kato,
Supervised by Hachiro Nakanishi (CMC, 1985,
“Nonlinear Optical Properties of
"Organic Molecule's and Crystals" Volumes 1 and 2, edited by DS Smura and Jay Jiss (Academic Press, 1987) "" Nonlinear Optical Properties of Organic Mo
lecules and Crystals "vol 1 and 2 DSChemla an
Edited by J. Zyss (Academic Press).

One of the applications of the non-linear optical material is a second harmonic generation (SHG) based on the second-order non-linear effect and a wavelength conversion device using a sum frequency and a difference frequency. So far, those which have been practically used are inorganic perovskites represented by lithium niobate. However, recently, it has become known that a π-electron conjugated organic compound having an electron-donating group and an electron-withdrawing group has various performances as a nonlinear optical material, which greatly exceeds the above-mentioned inorganic substances. For the formation of higher performance nonlinear optical materials,
It is necessary to arrange compounds having high nonlinear susceptibility in the molecular state so as not to generate inversion symmetry. It is known that a compound having a long π-electron conjugated chain is useful for the expression of a high non-linear susceptibility, which is one of them, and various compounds are described in the above-mentioned documents. Obviously, the maximum absorption wavelength becomes longer, and the transmittance of blue light decreases, for example, which hinders the generation of blue light as the second harmonic. This also occurs in the p-nitroaniline derivative, and the fact that the transmittance of the wavelength has a large influence on the efficiency of the second harmonic generation is due to Alain Azema et al., Proceedings of SPII, Four
Volume 00, New Optical Materials (Alain
Azema et al., Proceedings of SPIE, Volume 400, Now Op
Talical Materials), (1983) page 186, FIG.

Therefore, the advent of a nonlinear optical material having a high transmittance for blue light is desired. Conventionally, replacement of carbon atoms in the benzene nucleus of nitroaniline with nitrogen atoms has been studied, but satisfactory results have not necessarily been obtained. In addition, the applicant of the better method,
JP-A-62-210430 and JP-A-62-210
It was disclosed in Japanese Patent No. 432. Further, JP-A-62-599
34, JP-A-63-23136, JP-A-63-26
No. 638, Japanese Patent Publication No. 63-31768, and Japanese Patent Laid-Open No. 63-1.
63827, JP-A-63-146025, JP-A-6-
3-85526, JP-A-63-239427, JP-A-1-100521, JP-A-64-56425, JP-A-1-102529, JP-A-1-102530,
Many materials are disclosed in JP-A-1-237625, JP-A-1-207724 and the like. However, further improvement in blue light transmittance is desired.

[0005]

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a compound having a high blue light transmittance and a high nonlinear susceptibility in a molecular state.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have made a compound characterized in that an electron donor and an electron acceptor are bound to each other through at least one multiple bond. In, the electron acceptor is a compound comprising a group containing a boron atom (provided that the boron atom is not bonded to the terminal vinyl carbon of the open-chain styryl group, and the phosphorus atom is directly bonded to the vinyl group). It has been found that the objects of the present invention can be achieved by the compounds represented by the following general formulas (1) and (2).
General formula (1)

[0007]

[Chemical 3]

General formula (2)

[0009]

[Chemical 4]

Where R¹And R²Is an alkyl group, ant
Group and hydrogen atom. Z ¹And Z²Is Cal
Cogen atom and NR³Represents R³Is R¹and
R²Is synonymous with. W¹, W², W³And W^FourIs replaced
Represents a group, n¹And n³Is 0 to 4, n²and
n^FourRepresents an integer of 0 to 2.

The general formulas (1) and (2) will be described in more detail below. The alkyl group, R ₁ and R
₂ , R ₃ is, for example, a straight or branched chain having 1 to 24 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms (eg, methyl, ethyl, propyl, i
-Propyl, butyl, octyl, t-octyl). These may be substituted, and examples of the substituent include a hydroxy group and an alkoxy group (eg, methoxy, ethoxy, benzyloxy, 2-phenylethoxy,
2-methoxyethoxy), amino group (for example, amino, methylamino, dimethylamino, hydridino, piperidino, morpholino), acylamino group (for example, acetylamino, pivaloylamino, benzyloxycarbonylamino, benzoylamino, methanesulfonylamino, benzenesulfonylamino) , A carboxy group, an alkoxycarbonyl group (for example, methoxycarbonyl, i-propylcarbonyl, 2-methoxyethoxycarbonyl, 2-
Ethylhexyloxycarbonyl, cyclohexyloxycarbonyl), carbamoyl group (eg, carbamoyl, methylcarbamoyl, phenylcarbamoyl, benzylcarbamoyl), sulfamoyl group (eg, sulfamoyl, methylsulfamoyl, phenylsulfamoyl, benzylsulfamoyl), sulfo Group, an aryl group (eg, phenyl, tolyl, 1-naphthyl), a halogen atom (eg, fluorine, chlorine, bromine, iodine).

The aryl group has, for example, 6 carbon atoms.
To 30, preferably 6 to 16, and more preferably 6 to 11 (eg, phenyl, 1-naphthyl, 2-naphthyl and their substitution products),
Examples of the substituent include the alkyl groups (the above-mentioned substituted and unsubstituted alkyl groups) in addition to those described for the alkyl group.

Examples of the chalcogen include oxygen, sulfur, selenium and tellurium. W ¹ , W ² , W ³ and W
Examples of the substituent represented by ⁴ include those described in the section of the alkyl group and the aryl group described above.

Specific examples of the compound are shown below.

[0015]

[Chemical 5]

[0016]

[Chemical 6]

Basically, the synthesis of these compounds is described in W.
Steincop, H. Jacob, H.C. By Penz, Justus Liebigs Analendeer Hemmy 1934
Annual Volume 512, 136-164 (W. Steinkopf,
H. Jacob, H. Penz, JustasLiebigs Ann. Chem. 19
34, 512, 136-164). A specific example is shown below.

Synthesis Example 1: Synthesis of compound 1 2.4 equivalents of trimethylsilylacetylene, bis (triphenylphosphine) palladium (II) chloride complex (0.04 equivalents), and iodine were added to 1 equivalent of 3,4-dibromothiophene. Add 1.04 cuprous chloride to 1 in pyridine
The mixture was heated under reflux for 5 hours. 3,4-bis- with a yield of 85%
[(2-Trimethylsilyl) ethynyl] thiophene was obtained. Then, 0.4 equivalent of potassium carbonate was added to 1 equivalent of 3,4-bis-[(2-trimethyl) silylethynyl] thiophene, and the mixture was stirred in methanol at room temperature for 3.5 hours. 3,4-diethynylthiophene was obtained in a yield of 71%. Then, 1.1 equivalents of dibutyltin hydride, potassium hydroxide (0.5 equivalents) and 18-crown-6 (0.005 equivalents) were added to 1 equivalent of 3,4-diethynylthiophene, and the mixture was degassed in benzene. The mixture was stirred at room temperature for 2 hours. 1,1-Dinormal butyl thieno [3,4-d] stanepine was obtained with a yield of 85%. Then, dichlorophenylborane (3 equivalents) was added to 1 equivalent of 1,1-dinormal butylthieno [3,4-d] stanepine, and the mixture was stirred in degassed hexane under ice cooling for 10 minutes. Four
The target compound 1 was obtained with a yield of 0%. Melting point 165 ° C. (pale yellow, flaky crystal, recrystallized from benzene), λmax (cyclohexane) = 348 nm ¹ H-NMR (δppm in CDCl ₃ ) 7.35 (d, 2H), 7.44-7.50. (M, 3
H), 7.75 (s, 2H), 8.09 (d, 2H),
8.06-8.12 (m, 2H)

Synthesis Example 2: Synthesis of compound 2 10 g (0.041 mo) of 2,3-dibromothiophene
1) was dissolved in 300 ml of piperidine, and further 300 mg of cuprous iodide and 1.2 g of bis (triphenylphosphine) palladium (II) chloride complex were added. Trimethylsilylacetylene 12.9ml (0.091mo)
1) was added, and the mixture was heated under reflux for 4 hours under a nitrogen stream. After allowing to cool, 300 ml of n-hexane was added and the resulting precipitate was filtered off. After washing the filtrate with water, it was dried over magnesium sulfate,
Further purification by silica gel column chromatography gave 2,3-bis-[(2-trimethylsilyl) ethynyl] thiophene in a yield of 28%. Then a few
3.2 g (0.011 mol) of -bis [(2-trimethylsilyl) ethynyl] thiophene was dissolved in 130 ml of methanol, 620 mg of potassium carbonate was further added, and the mixture was stirred at room temperature under a nitrogen stream for 2.5 hours. Ether and water were added to the reaction mixture, and the separated organic layer was washed with water and dried over sodium sulfate. Purification by silica gel column chromatography gave 2,3-diethynylthiophene in 79% yield. 2,3-diethynylthiophene 0.85g
(6.4 mmol) was dissolved in 25 ml of benzene, 1.5 ml of dibutyltin hydride, 260 mg of potassium hydroxide and 30 mg of 18-crown-6 were sequentially added, and the mixture was stirred at room temperature for 2 hours under a nitrogen stream. Benzene and water were added to the reaction mixture, and the separated organic layer was washed with water and dried over magnesium sulfate. Purification was performed by silica gel column chromatography to obtain 1,1-dinormal butyl thieno [2,3-d] stanepine in a yield of 51%.

Next, 1,1-dinormal butyl [2,3
-D] Stanepine 707.4 mg (1.9 mmol)
It was dissolved in 3 ml of n-hexane and cooled in an ice bath. After 10 minutes, 650 mg of dichlorophenylborane (4.
1 mmol) was added all at once with stirring. After 10 minutes, the ice bath was removed and the temperature was raised to room temperature. The resulting solid was purified by a silica gel column to obtain the target compound 2 in a yield of 43%. Melting point 165.0-166.0 ° C (pale yellow, scaly crystal,
Recrystallized from benzene), λmax (cyclohexane) =
331 nm ¹ H-NMR (δppm in CDCl ₃ ) 7.4-7.5 (m, 4H), 7.56 (d, 1H) 7.81 (dd, 1H), 7.88 (dd-1H) ,
8.05-8.15 (m, 1H), 8.43 (d, 1
H) 8.44 (d, 1H)

The compounds according to the invention are, for example, in the form of powders, inclusions of molecules in the host lattice (polymers, inclusion compounds, solid solutions, liquid crystals), in the form of thin layers deposited on a support (Langmere. (Blodgett film etc.), single crystal form, solution form and the like, and can be used as the nonlinear optical material. Further, the compound of the present invention is a polymer in the form of a pendant,
It can also be used by binding to polydiacetylene or the like. For more information on these methods, see DJ William
It is described in the s edition.

When the compound of the present invention is used as a wavelength conversion element, for example, the following method is possible. 1. Single crystal of the above compound in the core of the fiber,
It is possible to create a wavelength conversion element using glass as a clad material and input YAG laser light to generate the second harmonic. Further, as another method, it is possible to generate a second harmonic wave by forming a waveguide type wavelength conversion element in the same manner. As the phase matching method at this time, the Thierenkov radiation method is used. However, the present invention is not limited to these, and waveguide-guided phase matching is also possible.

2. Next, the above compound can be made into a single crystal, a bulk single crystal can be cut out therefrom, and YAG laser light can be input to generate the second harmonic thereof. Angle phase matching is used as the phase matching method at this time. These bulk single crystals can be used not only outside the cavity of the laser but also inside the cavity of a solid-state laser such as an LD pumped solid-state laser to improve the wavelength conversion efficiency. Further, the wavelength conversion efficiency can be improved also by disposing it in the resonator of the external resonator type LD.

The Bridgman method, the solvent evaporation method and the like are used for the above single crystallization. The wavelength-converted wave is not limited to the second harmonic, but is also used for generating the third harmonic and the sum difference frequency. As a laser light source used as a fundamental wave at the time of wavelength conversion, for example, those shown in Table 1 can be mentioned. The wavelength of the fundamental wave is not limited except for the influence of the absorption of the above-mentioned material. This is Laser & Optronics 5
It is clear from page 9 (November, 1987).

[0025]

[Table 1]

[0026]

EXAMPLES The present invention will be described in more detail based on examples. Example 1 The molecular hyperpolarizability (β), which is the origin of the second-order nonlinear optical effect at the molecular level, was determined. Pallas N. Prarad, David J. WILLIAMS INTRODUCTION TO NONLINEAR OPTICAL EFFECT IN
Molecule's and Polymers (Paras N. Prasad
and Dauid J. Williams, Introduction to Nonlinear O
ptical Effects in Molecules and Polymers), John Wiley & Sons, Inc., Chapter 1 and Chapter 3 of 1991.
There are a method using molecular orbital calculation, a method using solvatochromism, an electric field induced SHG method, etc. Here, referring to the above-mentioned literature, a value regarding a dipole moment is obtained using the solvatochromism method, and oscillator strength and The transition energy was calculated from the absorption spectrum. Then, these values are applied to the two-level model equation (Equation 1) to obtain β
I asked. (Equation 1)

[0027]

[Equation 1]

[0028]

[Table 2]

It is clear from Table 2 that the compound of the present invention has a molecular hyperpolarizability (β) value higher than that of 4-nitroaniline which is already well known as a skeleton of an excellent organic nonlinear optical material. Therefore, the compound of the present invention has excellent properties as an organic nonlinear optical material.

Example 2 In order to evaluate blue light transmittance, an ultraviolet-visible absorption spectrum was measured. Table 3 shows the maximum absorption wavelength (λma) in the longest wavelength part.
x) and the shortest wavelength (λ ₀ ) at which the absorbance is substantially zero and the difference (Δλ) between them are shown.

[0031]

[Table 3]

[0032]

[Chemical 7]

From Table 3, the compound of the present invention is excellent in blue light transmittance, and because Δλ is small, it has a large molecular hyperpolarizability (β) as compared with an equivalent blue light transmitting compound. Predicted from the two-level model. Therefore,
The compound of the present invention has excellent properties as an organic nonlinear optical material.

Example 3 A second harmonic generation (SHG) experiment, which is a phenomenon based on the second-order nonlinear optical effect, was conducted. The following electric field oriented polymer films were prepared for the compounds 1, 2, 3 and 4-nitroaniline, and SHG was measured using the apparatus of FIG. -Method for preparing electric field oriented polymer film: For each 1 part by weight of each compound, 19 parts by weight of polymethylmethacrylate (PMMA, Amipec B manufactured by Sumitomo Chemical Co., Ltd.) and 250 parts by weight of acetone were weighed and made into a solution with stirring at room temperature. 2.5 ml of this solution was dropped on an ITO-coated glass substrate and spin-coated at 4000 rpm.
The film thickness was about 5 μm in each case. 60 this
After heating at 0 ° C. for 1 hour, electric field orientation was performed by the corona poling method.

The corona poling conditions were as follows: Voltage applied to corona wire: -10 kV Temperature: held at 105 ° C for 1.5 hours, then 4 ° C up to 40 ° C
After cooling for 5 minutes and aligning the electric field, SHG was measured immediately. The results are shown in Table 4.

[0036]

[Table 4]

As is clear from Table 4, the compounds of the present invention are useful as nonlinear optical materials.

[0038]

From the above examples, the compound of the present invention has a higher blue light transmittance and a sufficient SHG activity as compared with the compounds generally known as organic nonlinear optical materials. I understand. Therefore, the compound of the present invention is considered to be useful as a material for a wavelength conversion element, especially as a material for generating blue light.

However, the application of the nonlinear optical material of the present invention is not limited to the wavelength conversion element, and it can be used for any element as long as it utilizes the nonlinear optical effect. As specific examples of the element in which the nonlinear optical material of the present invention can be used, in addition to the wavelength conversion element, an optical bistable element (optical storage element, optical pulse waveform control element, optical limiter, differential amplification element, optical transistor, A / D) is used. Conversion element, optical ethics element, optical multivibrator, optical flip-flop circuit, etc.), optical modulation element, phase conjugate optical element and the like.

[Brief description of drawings]

FIG. 1 shows an apparatus for measuring SHG intensity by a powder method.

[Explanation of symbols]

 1 sample 2 fundamental wave cut filter 3 spectroscope 4 photomultiplier tube 5 amplifier 6 (11) wavelength 1.064 μm 7 (12) wavelength 0.532 μm

Claims (2)

[Claims] 1. At least one electron donor and at least one electron acceptor.
A non-linear optical material comprising a compound in which the electron acceptor comprises a group containing a boron atom, wherein the compound is bonded via multiple multiple bonds. However, the boron atom is not directly bonded to the terminal vinyl carbon of the open-chain styryl group, and the phosphorus atom is not directly bonded to the vinyl group. 2. The compound according to claim 1, wherein the compound is
Non-Linear Compounds Represented by Formulas (1) and (2)
Optical material. General formula (1)General formula (2)Where R¹And R²Is an alkyl group, an aryl group and
Represents a hydrogen atom. Z ¹And Z²Is the chalcogen atom
And NR³Represents R³Is R¹And R²Synonymous with
is there. W¹, W², W³And W^FourRepresents a substituent,
n¹And n³Is 0 to 4, n²And n^FourIs not 0
Represents an integer of 2.